Fig. 1. Principle of transmission K-domain transform digital holography 3D imaging technology. (a) Production process of illumination film; (b) digital holograms of off-axis interference; (c) intensity of illumination film at different axial depths; (d) three-dimensional amplitude of illuminated film

Fig. 2. Characteristic analysis of transmission K-domain transform digital holography 3D imaging technology. (a) Amplitude distribution of illumination film at focal plane; (b) coordinate transformation principle in K-domain; (c) object light intensity on x-z plane

Fig. 3. Schematic of high-pass filtering K-domain imaging. (a) Propagation direction of diffracted and illuminated light in x-z plane; (b) propagation direction of diffracted and illuminated light in y-z plane; (c) spatial spectrum of transmitted light

Fig. 4. K-domain transformation results of high-pass filtering. (a) Spatial spectrum of transmitted light after high-pass filtering; (b) spatial spectrum after K-domain transformation; (c) strength of x-z plane

Fig. 5. Transmission K-domain transform imaging without high-pass filtering. (a) Simulated sample image 1; (b) simulated sample image 2; (c) holograms; (d) spectrum on y-z plane; (f) intensity on y-z plane; (g) reconstructed image of sample 1; (h) reconstructed image of sample 2

Fig. 6. High pass filter transmission K-domain transform imaging results. (a) y-z plane intensity distribution; (b) reconstructed image 1 by high-pass filtering K-domain transform; (c) reconstructed image 2 by high-pass filtering K-domain transform

Fig. 7. Experimental optical path and experimental results. (a) Experimental equipment; (b) experimental sample; (c) microstructure of sample; (d) off-axis holograms; (e) spectrum of object light in x-y plane; (f) spectrum of object light on y-z plane; (g) intensity distribution on y-z plane; (h) reconstructed image of 1^st layer; (i) reconstructed image of 2^nd layer